The present invention is directed to devices and techniques for the surgical treatment of heart valve disease, and particularly aortic valve disease. The aortic valve separates the left ventricle of the heart from the aorta, which carries oxygenated blood to the arterial system. Normally, when the left ventricle contracts during systole, the aortic valve opens to allow blood to flow into the aorta. During diastole, when the left ventricle returns to its uncontracted state, the aortic valve closes to prevent blood from flowing from the aorta back into the heart.
In aortic valve disease, the aortic valve is compromised due to calcification of the valve leaflets, congenital deformation of the valve, or other conditions such that the valve does not completely open or close normally. As a result, the valve restricts blood flow out of the heart during systole, or the valve allows blood flow back into the heart during diastole. If the condition becomes sufficiently severe, surgical treatment is frequently required.
Various surgical techniques have been used to repair aortic valves. In conventional "open-chest" approaches, a large opening is formed in the chest--known as a sternotomy or thoracotomy--the patient's heart is arrested while circulation is supported by a cardiopulmonary bypass system, an incision is formed in the aorta, and instruments are then used to decalcify the valve, to separate valve leaflets which are fused together, or to constrict the annulus of an enlarged valve. Less-invasive approaches to valve repair have also been proposed. Balloon valvuloplasty, for example, involves the use of a balloon catheter threaded from a peripheral artery into the aorta, and expansion of a balloon within the calcified aortic valve to separate the valve leaflets while the heart remains beating. Unfortunately, aortic valve repair techniques have not had long-lasting success in preventing recurrence of the disease, and eventual replacement of the valve is frequently required.
The most widely-accepted surgical technique for the treatment of severe aortic valve disease is aortic valve replacement. In aortic valve replacement surgery, the diseased aortic valve is replaced with a prosthetic valve, homograft, allograft, or other type of replacement valve. Conventional aortic valve replacement techniques require a sternotomy or thoracotomy to be formed so as to provide access into and visualization of the chest cavity. The patient is placed on cardiopulmonary bypass, and the heart is stopped using an aortic cross-clamp to block blood flow through the aorta while a cardioplegic fluid is injected into the aorta upstream of the cross-clamp or into the coronary sinus on the venous side of the heart. An incision is then made in the ascending aorta near the aortic valve, and the native valve leaflets are removed using surgical scissors inserted through the aortic incision. Specialized instruments may also be used to debride the valve annulus. A replacement valve is then sutured in place at the native valve position.
While aortic valve replacement is frequently effective in treating aortic valve disease and can add ten or more years to the life of a patient having the disease, the procedure also suffers from significant drawbacks surrounding the invasiveness and trauma of the surgery. The large thoracotomy required by the procedure is highly invasive, produces a great deal of pain, heightens the risk of infection and other complications, increases costs, and lengthens hospital stay considerably.
What is needed, therefore, are devices and techniques for the surgical treatment of aortic valve disease, especially for performing aortic valve replacement, which do not suffer from the drawbacks of conventional open-chest aortic valve surgery. Most desirably, the devices and techniques should obviate the need for a sternotomy and minimize the size of any necessary thoracic incisions to eliminate the pain, trauma, risks, costs, and lengthy recovery time associated with conventional aortic valve surgery. At the same time, the devices and techniques should facilitate replacement of a diseased aortic valve with the same types of replacement valves which currently enjoy wide acceptance for aortic valve replacement, including mechanical valves, bioprosthetic valves, homografts, allografts, and others.